ChemistryChapter 16: Hydrocarbons
Alkenes and the C=c Bond — Isomers
But-1-ene vs but-2-ene (position).
Learning objectives
- Define isomers using accurate chemistry terms.
- Explain why isomers matters within alkenes and the c=c bond.
- Apply the learning unit to an FBISE-style example, comparison, diagram, or calculation.
Definition
But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page). This page separates the idea from the wider topic “ALKENES AND THE C=C BOND” so it can be revised and assessed on its own.
Formula
C=C BOND
Important terms
- ISOMERS
- But-1-ene vs but-2-ene (position).
- ALKENES AND THE C=C BOND
- Alkenes: C=C, unsaturated, CnH2n (one double bond, open).
Overview
Study this learning unit in three steps:
Key Idea
But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page).
Examples Position of C=C · Cis same side · Trans opposite
Exam Application
Exam: why no rotation about C=C? The pi bond would have to break. That costs energy at room T. So cis and trans can exist as different isomers.
Examples Position of C=C · Cis same side · Trans opposite
WHAT — ALKENES AND THE C=C BOND — ISOMERS
But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page). This page separates the idea from the wider topic “ALKENES AND THE C=C BOND” so it can be revised and assessed on its own.
WHY — Why this topic matters
ALKENES AND THE C=C BOND — ISOMERS is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW — How it works
But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page). Examples: Position of C=C; Cis same side; Trans opposite. Exam use: Exam: why no rotation about C=C? The pi bond would have to break. That costs energy at room T. So cis and trans can exist as different isomers.
Explanation
But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page). Examples: Position of C=C; Cis same side; Trans opposite. Exam use: Exam: why no rotation about C=C? The pi bond would have to break. That costs energy at room T. So cis and trans can exist as different isomers.
In simple words
Federal Board Class 11 Chemistry learning unit. Easy wording; no provincial-board material added.
Key points
- lock the double bond
- pi locks
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Alkenes and the C=c Bond — Isomers
Sticky Notes · Quick Revision
Core idea
- But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page). This page separates the idea from the wider topic “ALKENES AND THE C=C BOND” so it can be revised and assessed on its own.
WHAT
- But-1-ene vs but-2-ene (position).
WHY
- ALKENES AND THE C=C BOND — ISOMERS is an independent FBISE learning unit because students must use its definitions, conditions, equations, or trends separately in explanations and calculations.
HOW
- But-1-ene vs but-2-ene (position). Cis-but-2-ene vs trans. Functional? Not yet. Count H: C4H8 several isomers including cycloalkane. Geometric isomerism possible when each C has two different groups (later cis-trans page). Examples: Position of C=C; Cis same side; Trans opposite. Exam use: Exam: why no rotation about C=C? The pi bond would have to break. That costs energy at room T. So cis and trans can exist as different isomers.
Common misconception
- Do not treat isomers as the same as every other part of alkenes and the c=c bond; define this unit and use its own evidence, steps, or conditions.
FBISE exam check
- Define alkenes and the c=c bond — isomers, explain how it works, and support the answer with one relevant example.
60-second revision
- But-1-ene vs but-2-ene (position).
- Position of C=C
- Exam link: lock the double bond.
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